Siberian Federal University: Ancient DNA tells about the settlement of larch in the post-glacial period

An international research team, which included Konstantin Krutovsky, SibFU Honorary Professor, studied the dynamics of the distribution of two species of larch in Siberia after the end of the ice age. DNA analysis of sediment samples extracted from eight Siberian lakes helped to trace the movement of larch from the south to the north of the region.

Scientists believe that global climate change will lead to significant changes in the boreal forests of Siberia in the coming decades. Two species of larch from the genus Larix are considered predominant in these parts. Their ecosystem functions notably differ, so that their movements in certain ranges have global significance. However, until now, no studies have been conducted that would explain the reasons-drivers of the dynamics of the species composition of larch forests in the post-glacial period.

“The dynamics of the distribution of two species of larch — Siberian larch (Larix sibirica) and Gmelin larch (Larix gmelinii) on the border of the end of the last ice age is poorly studied, partly because paleoecological data on them are not available. The pollen is poorly preserved, but we have studied DNA fragments of trees of perennial bottom sediments collected from different depths of Siberian lakes and representing different historical periods, respectively. It turned out that the Siberian larch, currently dominant in Western Siberia, most likely migrated north during the Holocene period, about 10 thousand years ago. At the same time, samples belonging to the Pleistocene epoch, which is presently the last ice age on earth, dating back to the 21st millennium BC, have been identified as Gmelin larch. Our international research team led by Professor Ulrike Herzschuh, became first in the world to analyze a combination of nuclear repeats and chloroplast DNA in a broad time perspective to find out why larch species were distributed in this way”, reported Konstantin Krutovsky, co-author, SibFU Honorary Professor, Professor of the Department of Genomics and Bioinformatics of SibFU, Professor of the University of Göttingen.

Using modern methods of genetic analysis, the researchers concluded that larch forests began to dominate vast territories of Western and Eastern Siberia at the end of the last ice age. It turned out that the environment, in particular, permafrost, and not geographical factors such as limited settlement, had the greatest influence on larch forests.

Siberian larch became the dominant species during the Pleistocene, while the refugial populations (from the Latin refugium — shelter – an area of the earth’s surface or ocean, where a species or group of species experienced an unfavorable period for them, while in large areas these life forms disappeared) consisted mainly of Gmelin larch. When the glacier retreated, obeying climate warming, some Siberian larch also remained in shelters in the northern territories of Siberia, but the number of the species was not restored at all due to migration from these shelters. Larix sibirica moved from the southern territories, repopulating the once permafrost-bound spaces, while L. gmelinii populated the eastern territories from populations preserved during the ice age.

The findings are interesting both from a theoretical and practical points of view. With the help of specially synthesized short DNA fragments (oligonucleotides) identical to the genes of the chloroplast and nuclear genome of larch, DNA-DNA hybridization and targeted DNA enrichment were used for the first time to isolate, sequence and compare larch DNA in paleoobrazts of bottom sediments. This method turned out to help to differentiate numerous species of Larix with high accuracy and to trace the development and migration of different populations of this species over long periods of time. The DNA of the chloroplast genome is a promising object for genomic research, since it is present in abundance in almost all plant cells.

“Global warming, which is gaining momentum, currently affects mainly the high latitudes of the Northern Hemisphere, in particular, the Russian Arctic. We believe that these climatic changes will seriously affect the boreal forests of Siberia. Since larch currently makes up 81% of these forests, and larch forests serve as the basis for local ecosystems, provide carbon dioxide absorption and bring undoubted economic benefits to the Russian economy, in particular, the timber processing industry, it is necessary to closely study the dynamics of these species and their response to climate change in the past. This will help you predict what changes should be expected in the foreseeable future and prepare for them”, summed up Konstantin Krutovsky.

An international research team, which included Konstantin Krutovsky, SibFU Honorary Professor, studied the dynamics of the distribution of two species of larch in Siberia after the end of the ice age. DNA analysis of sediment samples extracted from eight Siberian lakes helped to trace the movement of larch from the south to the north of the region.

Scientists believe that global climate change will lead to significant changes in the boreal forests of Siberia in the coming decades. Two species of larch from the genus Larix are considered predominant in these parts. Their ecosystem functions notably differ, so that their movements in certain ranges have global significance. However, until now, no studies have been conducted that would explain the reasons-drivers of the dynamics of the species composition of larch forests in the post-glacial period.

“The dynamics of the distribution of two species of larch — Siberian larch (Larix sibirica) and Gmelin larch (Larix gmelinii) on the border of the end of the last ice age is poorly studied, partly because paleoecological data on them are not available. The pollen is poorly preserved, but we have studied DNA fragments of trees of perennial bottom sediments collected from different depths of Siberian lakes and representing different historical periods, respectively. It turned out that the Siberian larch, currently dominant in Western Siberia, most likely migrated north during the Holocene period, about 10 thousand years ago. At the same time, samples belonging to the Pleistocene epoch, which is presently the last ice age on earth, dating back to the 21st millennium BC, have been identified as Gmelin larch. Our international research team led by Professor Ulrike Herzschuh, became first in the world to analyze a combination of nuclear repeats and chloroplast DNA in a broad time perspective to find out why larch species were distributed in this way”, reported Konstantin Krutovsky, co-author, SibFU Honorary Professor, Professor of the Department of Genomics and Bioinformatics of SibFU, Professor of the University of Göttingen.

Using modern methods of genetic analysis, the researchers concluded that larch forests began to dominate vast territories of Western and Eastern Siberia at the end of the last ice age. It turned out that the environment, in particular, permafrost, and not geographical factors such as limited settlement, had the greatest influence on larch forests.

Siberian larch became the dominant species during the Pleistocene, while the refugial populations (from the Latin refugium — shelter – an area of the earth’s surface or ocean, where a species or group of species experienced an unfavorable period for them, while in large areas these life forms disappeared) consisted mainly of Gmelin larch. When the glacier retreated, obeying climate warming, some Siberian larch also remained in shelters in the northern territories of Siberia, but the number of the species was not restored at all due to migration from these shelters. Larix sibirica moved from the southern territories, repopulating the once permafrost-bound spaces, while L. gmelinii populated the eastern territories from populations preserved during the ice age.

The findings are interesting both from a theoretical and practical points of view. With the help of specially synthesized short DNA fragments (oligonucleotides) identical to the genes of the chloroplast and nuclear genome of larch, DNA-DNA hybridization and targeted DNA enrichment were used for the first time to isolate, sequence and compare larch DNA in paleoobrazts of bottom sediments. This method turned out to help to differentiate numerous species of Larix with high accuracy and to trace the development and migration of different populations of this species over long periods of time. The DNA of the chloroplast genome is a promising object for genomic research, since it is present in abundance in almost all plant cells.

“Global warming, which is gaining momentum, currently affects mainly the high latitudes of the Northern Hemisphere, in particular, the Russian Arctic. We believe that these climatic changes will seriously affect the boreal forests of Siberia. Since larch currently makes up 81% of these forests, and larch forests serve as the basis for local ecosystems, provide carbon dioxide absorption and bring undoubted economic benefits to the Russian economy, in particular, the timber processing industry, it is necessary to closely study the dynamics of these species and their response to climate change in the past. This will help you predict what changes should be expected in the foreseeable future and prepare for them”, summed up Konstantin Krutovsky.

Siberian Federal University
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